Musculoskeletal disorders include a group of conditions affecting the muscles, ligaments, tendons, nerves and other soft tissues and joints, caused or made worse by the work environment, which can differ in severity from mild periodic symptoms to severe chronic and debilitating conditions. A basic hypothesis exists that they are caused, aggravated or precipitated through a worker's exposure to vibration or the need to exert undesirable force, use uncomfortable hand grips, or adopt static awkward postures in the workplace, coupled with continuous repetitive work and insufficient rest or recovery. The term covers those conditions with specific medical diagnoses (e.g. frozen shoulder, carpal tunnel syndrome, hand-arm vibration syndrome), and the other conditions (often called Repetitive Strain Injuries) where there is pain without other specific symptoms.